Deaerating vacuum return receiver



Feb. 21, 1956 c. 1. BAKER 2,735,623

DEAERATING VACUUM RETURN RECEIVER Filed July 29, 1955 Q N w M INVENTOR. a, co C/YHALES BHKEE,

United States Patent 6 DEAERATING VACUUM RETURN RECEIVER Charles I. Baker, Pittsburgh, la.

Application July 29, 1955, Serial No. 525,314

6 Claims. (Cl. 237-68) This invention relates to steam heating systems, and more particularly to apparatus for deaerating the water in the system.

In a steam heating system the boiler water gathers latent heat and expands as it becomes steam. In the radiators of the system the steam gives up its latent heat and expansion as it condenses back to water. A return receiver collects this water of condensation and returns it to the boiler. This would all be satisfactory if it were not for the gases that are set free from the boiler water with the steam. These gases, mostly oxygen and carbon dioxide, carry no latent heat and are incondensable. They weaken the steam, form gas cells in distant radiators, and are entrained and redissolved in the condensate where they become corrosive and break down the steam heating system. These gases also are the main cause of cool radiators. Condensate from distant radiators will flow down return piping to the return receiver, but the gases will move only away from the steam pressure or towards a vacuum. Vacuum in return piping assures uniform heating and is as important for small steam heating systems as for large ones. It is necessary for low temperature deaeration.

It is among the objects of this invention to provide a return receiver for deaerating water in a steam heating system, which is inexpensive, which deaerates Well at relatively low temperatures, which is applicable to small as well as large systems, which requires only a few parts in addition to the usual components of a return receiver, and which is very simple in construction and operation.

In accordance with this invention a closed lower tank has a condensate inlet connected with the return piping of a steam heating system, while a closed upper tank has an outlet that leads to a boiler. There is a pump for delivering condensate periodically from the lower tank to the upper one. The tanks are also connected by a water conduit leading from the bottom of the upper tank to the lower tank and containing a normally closed re turn valve. A gas conduit connects the top of the lower tank with the upper tank and is provided with a check valve to prevent downward flow. The upper tank is provided with a vent in which there is a check valve that keeps air from flowing into the tank, as well as a valve that prevents condensate from escaping through the vent. Means are provided for operating the pump when the lower tank is nearly full of condensate, and there are means operated when the condensate falls to a predetermined low level for stopping the pump and opening the return valve until the condensate in the lower tank again is high enough for the pump to operate. The return valve is maintained closed while a predetermined low pressure in the lower tank exists. The condensate is received by the lower tank from the return piping, loaded with entrained and dissolved corrosive gases. The free and entrained gases separate from the condensate as they reach the return receiver. The dissolved gases are set free by vacuum in the lower tank and appear as minute bubbles within the condensate. As the condensate becomes quiet in the tank these bubbles rise to the surface and escape as free gases. I

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. l is a side view of my apparatus, and Fig. 2 is a wiring diagram of the electrical control circuit.

Referring to Fig. 1 of the drawings, condensate is returned from the steam heating system through a line 1 to the bottom of a lower horizontal closed tank 2. A check valve 3 is used in the return line when the lower tank is not at the lowest point of the line. The bottom of the tank also is provided with an outlet that is connected by a pump 4, driven by an electric motor 5, to a pipe 6 that extends up to an inlet in one end of an upper horizontal closed tank 7. The upper end of this pipe contains a check valve 8.

The bottom of the upper tank has an outlet connected to a line 10 that leads to the boiler of the system. This line generally contains a check valve 11. The bottom of the upper tank also is connected by a pipe 12 with the top of the lower tank to permit water to flow from the upper to the lower tank. This pipe contains a normally closed return valve 13, and has a branch tube 14 that communicates with a normally closed electric switch 15 that requires a predetermined low gas pressure or vacuurn to open it. Although the return valve may be operated in different ways, it is preferred to make it a magnetic valve that will be energized automatically when the pump is shut 01f.

The top of the lower tank is connected with the top of the upper tank by a pipe 17 for fiow of gases from the lower to the upper tank. This pipe contains a check valve 18 to prevent downward flow through the pipe. The top of the upper tank is provided with a vent, on which an inverted check valve 19 is mounted. This valve contains a vertically movable valve closure disc 21 that normally is in its lower open position. A small vent pipe 22 leads away from the top of this valve and contains a small check valve 23 to prevent flow of air into the tank. For a purpose that will be described later, the opening through valve 23 is considerably smaller than the one through valve 19.

Inside of the lower tank there is a float 25 connected by an arm 26 to a rock shaft 27 in an electric switch 28 mounted on the end of the tank. As shown in Fig. 2, the switch preferably includes a mercury tube 29, rigidly mounted on the rock shaft. The opposite ends of the tube contain pairs of electric contacts 30 and31, respectively. When the float is in its upper position at high liquid level, contacts 30 are closed and the pump motor is energized through wires 32, 33 and 34. When the float falls to the low liquid level, the mercury tube is tilted to open the motor circuit and to close the magnetic return valve circuit through wires 36, 37, 38' and 39 and vacuum controlled switch 15. If the last switch happens to be open, as will be explained later, the return valve cannot open but the operation of the pump circuit will not be alTected.

While this apparatus is in operation, condensate collects in the lower tank until the liquid level is only a few inches from the top of the tank. The float 25, in its upper position, tilts the mercury switch far enough to cause current to be delivered to the pump motor, whereupon condensate is pumped from the lower tank to the upper one. As the liquid level in the lower tank falls, the displacement of condensate draws gases and more condensate from the return line 1 into the tank. The quantity of condensate received may vary, but the pump must run until a unit volume of gases has been received by the lower tank, which will fill it to low liquid level. By

3 that time the switch 28 will be tripped by the lowered float and the pump shut 0E and the magnetic return valve 13 opened.

Condensate in the upper tank now will return by gravity through the water pipe 12 to the lower tank, thereby forcing the gases from the lower tank up through the gas pipe 17 to the upper tank. As soon as the liquid level in the lower tank has again risen high enough, the raised float will cause current to be switched from the return valve to the pump and the self-closing return valve will close the water pipe. Again the pump will begin moving condensate from the lower to the upper tank, and this displacement will continue until a second unit volume of gases is received by the lower tank from return line 1. During this period, the condensate being pumped into the upper tank forces the first unit volume of gases therein out through the top vent to atmosphere. In other words, as gas pressure slowly builds up in the upper tank, the gases start to discharge slowly to atmosphere through the vent. stricts the discharge, so the gas pressure becomes practically the same on top of valve disc 21 as below it and that valve 19 remains open to discharge of gases. On the other hand, when the condensate level in the upper tank, which rises quite rapidly, strikes valve disc 21, the

force of the liquid will lift it and close valve 19 until return valve 13 opens. Any excess condensate that arrives after valve 19 has been closed by a full tank of condensate, is discharged through outlet line 10 to boiler.

As soon as the condensate in the upper tank has returned through the opened return valve 13 to the lower tank and forced the gases from the lower to the upper tank through gas pipe 17, those gases will be discharged to atmosphere by the condensate which will then be pumped into the upper tank from the lower one.

This repeated cycle of power and gravity displacement of condensate from one tank to the other creates vacuum in the lower tank and return lines, separates corrosive gases from the condensate, condenses any steam flashing, discharges gases to the atmosphere and pumps excess condensate to the boiler line 10. Such displacement back and forth between the tanks continues until sufiicient vacuum has been created in the return lines and lower tank to open the vacuum controlled switch 15. Now, when electric current is switched from the pump to the return valve circuit, that valve 13 will not be energized and opened. Condensate will be detained in the upper tank and liquid displacement for creating vacuum cannot begin again until a predetermined reduction in vacuum permits the vacuum switch to close in order to open the return valve. In the meantime, however, if condensate received by the lower tank from the return line rises to high liquid level, the pump will be set in operation to deliver condensate through the upper tank to the boiler.

A definite quantity of condensate is required for the power and gravity displacement operations. During these operations, condensate also is withdrawn from the return line. The additional condensate thus received becomes excess and an equal quantity is forced to boiler from the upper tank. The apparatus may be adjusted to have the upper float level, indicated by the upper horizontal broken line in the lower tank, at any desired height. The closer the condensate is allowed to approach the top of the tank, the quicker the air pressure inside the tank will be reduced as the condensate is pumped out.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A return receiver for deaerating water in a steam heating system, comprising a closed lower tank having a The small check valve 18 recondensate inlet, a closed upper tank having an outlet adapted to lead to a boiler, a pump having an inlet connected with the lower tank and an outlet connected with the upper tank for delivering condensate from the lower tank to the upper tank, a Water conduit connecting the bottom of the upper tank with the lower tank, a normally closed return valve in said conduit, a gas conduit connecting the top of the lower tank with the upper tank, a check valve in the gas conduit preventing downward flow, a vent connected with the top of the upper tank, a check valve in the vent preventing air flow into the upper tank, means for operating the pump when the lower tank is substantially full of condensate, and means operated when the condensate in the lower tank falls to a predetermined low level for stopping the pump and opening said return valve until the condensate in the lower tank again is high enough for the pump to operate.

2. A return receiver according to claim 1, including a check valve preventing flew back through the pump to the lower tank.

3. A return receiver for deaerating water in a steam heating system, comprising a closed lower tank having a condensate inlet, a closed upper tank having an outlet adapted to lead to a boiler, a pump having an inlet connected with the lower tank and an outlet connected with the upper tank for delivering condensate from the lower tank to the upper tank, a water conduit connecting the bottom of the upper tank with the lower tank, a normally closed return valve in said conduit, a gas conduit connecting the top of the lower tank with the upper tank, a check valve in the gas conduit preventing downward flow, a vent connected with the top of the upper tank, a liquid flow operated valve in the upper tank for closing the vent when that tank is full of condensate, a check valve in the vent beyond the liquid flow operated valve for preventing air tlow into the upper tank, means for operating the pump when the lower tank is nearly full of condensate, and means operated when the condensate in the lower tank falls to a predetermined low level for stopping the pump and opening said return valve until the condensate in the lower tank again is high enough for the pump to operate.

4. A return receiver for deaerating water in a steam heating system, comprising a closed lower tank having a condensate inlet, a closed upper tank having an outlet adapted to lead to a boiler, a pump having an inlet connected with the lower tank and an outlet connected with the upper tank for delivering condensate from the lower tank to the upper tank, a water conduit connecting the bottom of the upper tank with the lower tank, a normally closed return valve in said conduit, a gas conduit connecting the top of the lower tank with the upper tank, a check valve in the gas conduit preventing downward flow, a vent connected with the top of the upper tank, a check valve in the vent preventing air flow into the upper tank, means for operating the pump when the lower tank is nearly full of condensate, means operated when the condensate in the lower tank falls to a. predetermined low level for stopping the pump and opening said return valve until the condensate in the lower tank again is high enough for the pump to operate, and means responsive to a predetermined low pressure in the lower tank for maintaining said return valve closed until said pressure rises to a predetermined value again.

5. A return receiver for deaerating water in a steam heating system, comprising a closed lower tank having a condensate inlet, a closed upper tank having an outlet adapted to lead to a boiler, a pump having an inlet connected with the lower tank and an outlet connected with the upper tank for delivering condensate from the lower tank to the upper tank, a water conduit connecting the bottom of the upper tank with the lower tank, a normally closed electrically operable valve in said conduit, a normally open electric circuit connected with said valve, a gas conduit connecting the top of the lower tank with the upper tank, a check valve in the gas conduit preventing downward flow, a vent connected with the top of the upper tank, a check valve in the vent preventing air flow into the upper tank, an electric motor for operating the pump when the lower tank is nearly full of condensate to pump it up into the upper tank, an electric circuit connected with the motor, and electric switching means controlled by the condensate in the lower tank when it falls to a predetermined low level for opening the motor circuit and closing the electric valve circuit 1 until the condensate in the lower tank again is high enough for the switching means to be reversed.

6. A return receiver according to claim 5, including means responsive to a predetermined low pressure in the lower tank for maintaining the electric valve circuit open until said pressure rises to a predetermined value again.

References Cited in the file of this patent UNITED STATES PATENTS 900,814 Wilson Oct. 13, 1908 1,802,384 Jarvis Apr. 28, 1931 1,988,382 Greene Jan. 15, 1935 2,277,977 Hesse Mar. 31, 1942 

